About the Book: In the second thrilling installment of this magical middle-grade mystery series, anxious but brave Miss Mary-Kate Martin travels to the mythical Greek island of Galinios with her archaeologist mother. While Professor Martin investigates a newly discovered ancient mosaic, Mary-Kate’s relaxing holiday takes a twist when a mysterious message calls her to solve a legendary sea monster mystery. As whispers of the Two-Headed Hydra emerge, Mary-Kate teams up with a local boy, Nikos, to uncover the truth behind the creature’s sudden rage. Filled with humor, heart, and fantasy, this delightful adventure blends mythology, magical realism, and monster lore—perfect for curious young readers. From the award-winning author of Lenny’s Book of Everything, this story champions courage, friendship, and emotional resilience in the face of fear.